Various user devices such as mobile phones have a user interface. Typical mobile phones have a plurality of keys and/or a touch screen for receiving user input. Hands-free sets are provided for listening to music with mobile phones and for convenient telephone conversations. Hands-free sets designed for mobile phones typically have one or more keys for answering phone calls, adjusting volume, play/pause, for instance. In wired hands-free sets, there is a cable that connects headphones and a microphone to the mobile phone and that has housing for the keys usually near the neck of the user when in use.
Some wireless headsets have a radio transceiver in a housing that contains a microphone, a headphone and a support for holding the headphone in place. The housing of such headsets typically has one or more keys as user controls. There are also some wired hands-free sets where user controls are located at one or two headphones.